Means for use in making angular adjustments and measurements



Jan. 14, 1936. c. ALLAN 2,028,034

MEANS FOR USE IN MAKING ANGULAR ADJUSTMENTS AND MEASUREMENTS Filed Jan. 12,1935

Inventor 672617165 (y/(Z (i/[all P M Attorney.

UNITED STATES PATENT OFFICE MEANS FOR USE IN MAKING ANGULAR ADJUSTMENTS AND MEASUREMENTS Charles Cyril Allan, Pietermaritzburg, Natal, Union of South Africa Application January 12, 1935, Serial No. 1,581 In Union of South Africa October 23, 1934 5 Claims. 01. 33-69) This invention relates to means for use in makthe possibility of slip or play and consequent mg angular adjustments and measurements, such inaccurate measurement. As an alternative for as required, for example, in theodolites, sextants, e same p p the track and/or the ro r protractors and like instruments. 7 wheel may be magnetized so as to be under con- At present, such instruments generally emstant attraction towards each other. Screw or body a fixed graduated ring or arcuate member other means may al be ded for adjustin with which cooperates a. Vernier or micrometer the distance of the roller or wheel from the comcarried by a part of the instrument turnable with mon cen e of rotat o the aide the eof and respect to the said ring or member. The graduthe track, proper adjustment being p b y 10 ated ring or member and the vernier or micromffected initially by the maker of the instrument 10 eter are, however, comparatively expensive to and a screw or other device being provided for manufacture and involve th use of a, mi rofixing or setting the roller or wheel in the correct scope, which makes it cumbersome to read the position.

graduations, especially in a dull light, and. may Means embodying the invention will now be degive rise to errors. scribed, by way of example, with reference toile 15 The object of the present invention is to elimiannexed drawin in Whi h:- A hate these drawbacks and provide an inexpensive F g. 1 is a front View of the indicator used in means whereby the reading can be made readily uc mea s; and accurately. Fig. 2 is a cross-sectional side elevation of the According to the invention, I provide means for means, partly broken w y; 20 making angular measurements or adjustments in 3 is a P V Corresponding to F which the parts of the instrument to be turned Referring to the s=- relatively to each other are provided respectively The roller l is formed integral W h a e with a circular, arcuate or other running track 2 and it in frictional Contact with a fixed and a wheel or roller adapted to roll upon, or 1.111191 track The base 4, Whereon the track is 25 be rotated by, the said track, an indicating pointformed, rotatably pp a turntable the axis e or lik l t or 1 t being operated by of rotation of such table and the centre of the 'such roller or wheel, through the intermediary, track 3 being d nt w th each other.

if desired, of gearing, so a t gi di e t, 13133.. The axle 2 carries a toothed wheel 6 which else indication or measurement of the relative meshes Withotoothed Wheel Carried byespindle 30 angular movement of the aforesaid parts, readb ari g a large pointer 9 o its ou r n able with the aked, y Such pointer is adapted to cooperate with a large If desired, the track may be fixed and the wheel graduated dial Which, in Practice, is a e or roller carried by n axl r member adapted to represent one degree divided into minutes, each to swing about an axis coincident or substanminute being subdivided into fractions e c r p- 5 tially coincident, with that of the track. Preferresenting w y s nd At th outer end f the ably, the relative peripheries of the roller or wheel axle a small Pointer l l is p v adapted to and the track are so made that, with or without coope ate W th a miniature dial marked to gearing, an indication or measurement of th represent ten units of degrees. The toothed wheel 40 gular movement can'be obtained on a dial or dials 7 is adapted to drive a tOOthed Wheel Secured 40 in degrees, minutes and seconds, and/or th r on a spindle l4 carrying a small pointer l5. For known units. In practice, the means may h ve co-operation therewith, a miniature dial I6 is a large dial graduated to represent one degree P v e graduated to ep esent 360 divided in minutes and seconds, and two miniature dials into tens of degrees. Aswill be understood,

marked within the face thereof, one graduated to the case of the peripheries of the roller I and 45 represent one revolution of the track and the track 3 being made in the ratio one to thirty-six, axis of the wheel or roller relatively to each other the relative number of teeth in the wheels 6, I in tens of degrees, and the other to represent and I3 should be one hundred, d three a fraction of such revolution in degree units. hundr d a d Sixty, respectively.

The driving contact between the wheel or roller The indicator casing I1 is carried by a pair of and thetrack may beobtained byfriction of their arms l8 fixed to a bracket IS, in which, also, is surfaces and spring or other resilient means may journalled the inner end of. the axle 2. The be provided to maintain a constant yielding'presbracket I9 is secured on the outer end of an arm sure between the contacting surfaces of the wheel 20, formed with a saw-cut 2| so as to render the or roller and the track, so as to obviate or reduce outer portion thereof springy relative to the inner 55 7 centre.

( a spring bufier 23, the pressure of which can be varied by a screw 24 threaded through a screwed opening in a spring-bracket 25. A screw-pin 2B secures both the arm 20 and the bracket 25 on the turntable 5. For the purpose of adjusting the roller I radially with respect to the track 3, the arm 20 is provided with an upstanding lug 21, through which, and a relatively fixed bracket 28,

a screw-bolt 29 passes, so that, when the screwpin 2G is slackened, the arm 20 can be moved lengthwise by turning a knurled nut 30, the spring 3| exerting a constant pressure on the lug 21 outwardly from the bracket 23.

Various modifications may be made in the means described without departing from the scope of the invention. For example, the roller or wheel and the track may be provided with intermeshing teeth, and whether a toothed or friction drive is relied upon the roller or wheel may, in contrast to the construction described, be adapted to rotate about a fixed axis while the track rotates along with one of the angularly movable parts, or, as a further alternative, both the track and the arm carrying the roller or wheel may be independently rotatable about a common Preferably, the track in the case of a friction drive is made of frosted glass, agate, or similar hard substance, while the roller or wheel is made of phosphor bronze or like metal or material adapted to exert a satisfactory frictional grip on the track. In the case .of toothed gearing, the track maybe made of steel and the wheel rather of steel or other substance such as phosphor bronze. Amongst other modifications, which may be made in the means described, may be mentioned the coating with luminous paint of the pointer or other indicating element or elements, and the units and graduations on the dial or dials, so as to be readily readable in the dark.

Whilst the invention has been described as 'of general application to the measurement of angles, it will be understood that, in respect of any particular instrument, incidental modifications may be made. For example, in the case of a theodolite, the track may take the place of, or be constituted by, the ordinary graduated fixed horizontal circle, and the roller or wheel may be carried on an axle mounted on the usual horizontal turntable, which also carries the gearing and indicating dial. Moreover, the invention may be applied to the means for adjusting the telescope of the theodolite about its horizontal axis, in which case, the track may take the place of, or be constituted by, the usual graduated vertical circle, and the roller or wheel may be carried on an axis fixed relatively to the supports of the arc, such supports, or the turntable bearing them, also carrying the cor responding gearing and dial.

In the application of the invention to a protractor, the circular or semi-circular portion thereof may constitute the track, and the roller or wheel be carried in an arm adapted to swing about the centre from which the circular or semi-- circular portion is struck, such arm or an extension thereof being also provided with a dic pressible pin or marker which can be operated to mark off any particular angle as indicated or measuredby the pointer operated from the rolle or wheel. H r

I claim:-

1. Means for use in measuring angular move- 7 relative to each other, resilient means for maintaining a constant yielding pressure between the contacting surfaces of the wheel and track to obviate slip or play, and indicating means operable by said wheel to give a direct precise measurement of the relative angular movement of said elements readable with the naked eye.

2. Means for use in measuring angular movement between relatively rotatable elements comprising, in combination, a track associated with one of said elements, a wheel associated with the other of said elements so that upon relative rotation of said elements, said track and wheel roll relative to each other, resilient means for maintaining constant yielding pressure between the contacting surfaces of said wheel and track to obviate slip or play, a device for adjusting the distance of the wheel from the common centre of rotation of the axis thereof and the track, and indicating means operable by said wheel to give a direct precise measurement of the relative movement of said elements readable with the naked eye.

3. Means for use in measuring angular movement between relatively rotatable elements comprising, in combination, a track associated with one of said elements, a wheel associated with the other of said elements so that, on relative rotation of said elements, said track and wheel will roll relative to each other, a leaf spring for maintaining a constant yielding pressure between the contacting siu'faces of the wheel and track to obviate slip or play, and indicating means operable by said wheel to give a direct, precise measurement of the relative angular movement of said elements, readable with the naked eye.

4. Means for use in measuring angular movement between relatively rotatable elements comprising, in combination, a track associated with one of said elements, a wheel associated with the other of said elements so that, on relative rotation of said elements, said track and wheel will roll relative to each other, a leaf springfor maintaining a constant yielding pressure between the contacting surfaces of the wheel and track to obviate slip or play, means for adjusting said pressure, and indicating means operable by said wheel to give a direct, precise measurement of the relativeangular movement of said elements, readable with the naked eye.

a ,5; Means for use in measuring angular movementbetween relatively rotatable elements comprising, in combination, a track associated with one of said elements, a wheel associated with the otherof said elements so that, onrelative rotation of said elements, said track and wheel will roll relative to each other, a carrier for said wheel,.screw means to adjust said carrier relative to thecentre of said track, means for fixing said carrier in adjusted position, and indicating means operableiby' said wheel to give a direct precise measurement of the relative movement of said elements, readable with the naked eye.

- 7 r CHARLES CYRIL ALLAN. 

